Information recording method, information recording medium and information recording apparatus

ABSTRACT

A recording medium for use with an information recording apparatus which has a timing adjusting controller to adjust a timing of a recording pulse having a disk-like substrate. At least one track is provided on the disk-like substrate and a zone is provided which includes the at least one track. The zone stores information relating to a predetermined timing of a pulse for the recording medium which is detected by the apparatus.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This is a continuation of U.S. application Ser. No. 09/695,089,filed Oct. 25, 2000, which is a continuation of U.S. application Ser.No. 09/366,641, filed Aug. 4, 1999, now U.S. Pat. No. 6,160,784, thesubject matter of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to information recording methodsand apparatuses which use a medium for recording information byirradiating an energy beam and more particularly, to an informationrecording method and medium which can exhibit excellent effects on aphase transition optical disk as well as to an information recordingapparatus based on the information recording method.

[0003] In a related art method for performing recording and erasingoperations over a rewritable recording film, for example, when anoptical disk is used which has an exchange coupling two-layer film as arecording film as disclosed in U.S. Pat. No. 5,475,657, or when a phasetransition type optical disk recording film is used which can eraseinformation at high speed by realizing crystallization in substantiallythe same time as a laser irradiation time for recording as disclosed inJP-A-62259229 (laid-open on Nov. 11, 1987); the recording and erasingare carried out by changing energy of one energy beam to one of at leasttwo levels higher than a reading power level, that is, by changing theenergy of the energy beam to one of at least a high power level and anintermediate power level. This method is advantageous in that so-calledoverwriting (rewriting based on overwriting) of recording newinformation while erasing existing information can be realized. Further,as disclosed in JP-A-62259229 and JP-A-3-185629 (laid-open on Aug. 13,1991), such a phenomenon that a recording mark becomes a tear drop shapecan be suppressed (a backward width of the recording mark becomes largerthan a forward width thereof) by changing the energy of an energy beaminto one of three power levels, that is, high and intermediate levelsand a level lower than the intermediate level.

[0004] In recent years, there has been put in practical use a DVD-RAM(digital video disk-random access memory) which uses a 120 mm-diametereddisk made of phase transition material and having a memory capacity of2.6 GB on its one side. A recording control method employed in thisexample is as shown in FIG. 1 and is explained as DVD Specification forRewritable Disc (DVD-RAM), Part 1, Physical Specifications, version 1.0(July, 1997), Page PHX-9, FIG. 1.

[0005] JP-A-63-48617 (laid-open on Mar. 1, 1988) also discloses a methodfor changing an energy beam depending on a mark length (corresponding toa region length in a second state in claims at the time of itsapplication) or on a space length (corresponding to a region length in afirst state in claims at the time of its application).

[0006] Also disclosed in JP-A-8-287465 (laid-open on Nov. 1, 1996) is amethod for converting an energy beam to a multi-pulsed train dependingon a mark length or a space length.

SUMMARY OF THE INVENTION

[0007] Studies concerning achievement of a higher density of rewritabledigital video disk (DVD-RAM) using a phase transition recording filmhave recently been advanced. With such an optical disk device as toperform mark edge recording over a phase transition recording film as inDVD-RAM, it is required for the purpose of avoiding mark shapedistortion or missing of erasing recorded marks that an achievedtemperature and a cooling rate in a record mode are substantially thesame even in any outer edge of a region of a recording film melted forformation of a recording mark. However, methods proposed so far failedto satisfy the above condition sufficiently in their various recordingwaveforms and were limited in their achievable recording densities.Further, recording characteristics of information recording mediumusually vary with medium manufacturers, manufacturing times and lots.Thus as it is desired to obtain higher density recording, it becomesmore difficult to secure a recording compatibility therebetween.

[0008] In particular, in the case of a DVD-RAM having a recordingcapacity of 4.7 GB higher in density than a DVD-RAM having a recordingcapacity of 2.6 GB, when recording is carried out with the same spotdiameter as in the 2.6 GB DVD-RAM, compatibility with the 2.6 GB DVD-RAMcan be achieved more easily. However, as a linear density is increasedwith the same spot used, a spacing between positions at which twoadjacent recording pulses are irradiated on the recording medium becomessmaller than the spot diameter of a laser beam on the medium. Therefore,since light distribution is overlapped when compared with the 2.6 GBcase, it becomes necessary to prevent distortion of a recording markshape caused by the overlapping. Moreover, when a space betweenrecording marks is small, impossible separation between the marks with areading beam spot causes a shift of a recording mark edge position of areproduction signal waveform, it is also required to prevent such ashift. The edge position shifting way depends largely on the design ofthe recording medium, and the recording waveform suitable for a specificrecording medium is not always suitable for another recording medium. Incurrent circumstances, because of the increased linear density, therecording mark edge shift is increased by a mismatch between therecording medium and recording waveform to such a level as not to benegligible.

[0009] It is therefore an object of the present invention to provide amethod and apparatus which can accurately record information with use ofthe same spot and can increase its density while attaining acompatibility. A related object of the present invention is to providean information recording method, medium and apparatus which can stablyrecord information on various sorts of recording media having differentcharacteristics and also can easily secure a recording compatibilitytherebetween.

[0010] In order to attain the above objects, an information recordingmethod, medium and apparatus which follow are used.

[0011] 1) An information recording method wherein a single recordingmark is formed on a recording medium with use of a train of a pluralityof energy beam pulses, and any of a first case where a falling edgetiming of a head pulse in the energy beam pulse train is substantiallystationary while a rising edge timing thereof is varied and a secondcase where the rising and falling edge timings of the head pulse arevaried, is used to record information on the basis of control datapreviously recorded on the recording medium.

[0012] 2) An information recording apparatus which comprises an energybeam generator; a power adjustment mechanism for adjusting a power levelof an energy beam generated by the energy beam generator; a holdermechanism for holding a recording medium; a movement mechanism forrelatively moving the energy beam and the recording medium; a signalprocessing circuit for changing information to be recorded to the powerlevel of the energy beam; first timing adjustment means for causing thepower adjustment mechanism to control the energy beam generator togenerate a train of a plurality of energy beam pulses from thegenerator, for substantially fixing a falling edge timing of a headpulse in the energy beam pulse train, and at the same time for changinga rising edge timing thereof on the basis of control data previouslyrecorded on the recording medium at time of forming a single recordingmedium on the recording medium; and second timing adjustment means forchanging the rising and falling edge timings of the head pulse.

[0013] 3) An information recording method which includes at least one ofmethods 1 and 2 and uses a recording medium capable of forming a firststate zone with a first power level of an energy beam and a second statezone with a second power level of the energy beam higher than the firstpower level, wherein the energy beam and the recording medium arerelatively moved to irradiate the energy beam on the recording mediumand to form the first and second state zones with predetermined lengthsand with a predetermined spacing therebetween on-the recording medium torecord information on the recording medium, a third power level lowerthan the second power level is provided, and at the time of forming thesecond state zone having a specific length on the recording medium, aduration of the third power level is included as mixed in a duration ofthe second power level to convert the energy beam to a multi-pulsedtrain and to irradiate the energy beam on the recording medium, themethod 1 substantially fixes a falling edge position of a head pulse inthe multi-pulsed train and moves a rising edge position thereof at thetime of forming the second state zone having a specific length, themethod 2 substantially fixes a rising edge position of a tail pulse ofthe multi-pulsed train and moves a falling edge position thereof at thetime of forming the second state zone having the specific length, afourth power level equal to or lower than the first power level isprovided, the power level of the energy beam following the tail pulse ofthe multi-pulsed train is kept at the fourth power level for apredetermined time and then kept at the first power level, and a timeduring which the fourth power level is kept is always constantregardless of the falling edge position of the tail pulse.

[0014] Since the above recording methods set forth in the above 1) and2), information recording apparatus and corresponding informationrecording media are employed, the timing adjustment means alwayssuitable for the information recording medium can be selected andinformation can be recorded therein always stably.

[0015] Since the above recording method of the above 3) is used, thetime during which the constant fourth power level is maintained can bealways realized for the information recording medium regardless of thetiming adjustment. Therefore, since thermal conditions always optimumfor the information recording medium can be maintained, information canbe recorded in the medium always stably.

[0016] Explanation will be made as to methods, apparatuses and recordingmedia for recording information always stably in connection withembodiments which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 shows how to record information in a recording strategy towhich the present invention is applied;

[0018]FIGS. 2A and 2B show experimental results in a case 2 in therecording strategy to which the present invention is applied;

[0019]FIGS. 3A and 3B show experimental results in a case 2 in therecording strategy to which the present invention is applied;

[0020]FIGS. 4A and 4B show experimental results in a case 1 in therecording strategy to which the present invention is applied;

[0021]FIGS. 5A and 5B show experimental results in the case 1 in therecording strategy to which the present invention is applied; and

[0022]FIG. 6 shows specific examples of an information recording mediumand apparatus to which the present invention is applied.

DESCRIPTION OF THE EMBODIMENTS

[0023] Explanation will be first be made as to reference numerals usedherein.

[0024] Reference numeral 100 denotes a recording medium, 108 a casing,110 a motor, 111 a rotary shaft, 112 a chucking mechanism, 115 a rail,116 a rail guide, 117 a case, 118 a rotating motor, 119 a linear gear,120 a rotary gear, 121 a magnet, 122 a coil, 123 a suspension, 130 anobjective lens, 131 semiconductor laser, 132 a collimating lens, 133 abeam splitter, 134 a detection lens, 135 a photodetector, 140 adetector, 141 a detection switch, 150 a system controller, 151 a servocontroller, 152 a amplifier, 153 a decoder, 153 a decoder, 154 a signalprocessing circuit, 155 a timing controller or delay circuit, 156 acurrent sink, 157 a constant or fixed current controller, 158 a outputconnector, 159 an input connector, 160 a terminal, 161 a signalprocessing circuit.

[0025] The present invention will next be explained in accordance withembodiments which follow.

[0026] Shown in FIG. 1 are variations with time in the power level of anenergy beam irradiated on a recording medium at the time of recordinginformation on the recording medium. In this embodiment, how to changethe power level at the time of recording information with time isreferred to generally as write or recording strategy. FIG. 1 shows arecording strategy including an information recording method of thepresent invention. The present embodiment will be explained inconnection with a DVD-RAM as a specific example. In the case of theDVD-RAM, assuming that a reference clock in recording and reproductionmodes has a time width Tw, then the shortest mark and/or space has alength of 3Tw (time length of 3 times as long as the time Tw), and thelongest mark and/or space has usually a length of 11tw and in a specialcase, of 14Tw.

[0027] When an NRZI signal as information is given to be recorded on therecording medium in a time series manner, a suitable signal processingcircuit converts the NRZI signal to a time series variation in the powerlevel of an energy beam, which variation is shown in FIG. 1 as an lightpulse waveform. The power level is set to have 4 levels of write level,bias level 1, bias level 2 and bias level 3. At the bias level 1, thestate of the recording medium having the energy beam applied thereat canbe placed in a first state; while at the write level, the recordingmedium can be placed in a second state. The bias level 3 is set to beequal to or lower than the bias level 1, when it is desired to form asecond state area or zone in the recording medium and the second statearea has a length of 4Tw or more (that is, the NRZI signal has a lengthof 4Tw or more), a duration having the power level of the bias level 3is mixedly placed in the irradiation period of the write level to changethe energy beam in a multi-pulsed form. In the multi-pulsed energy beam,the first and last light pulses are referred to as the head or first andtail or last pulses respectively. Between the head and tail pulses,light pulses are repeated between the write level and bias level 3. Therepetition frequency, when the NRZI signal has a length of n (n>3),becomes (n−4). The entire repetitive pulses between the head and tailpulses will be generally called a comb-shaped pulse. Accordingly, whenit is desired to form a second state area for the NRZI signal having alength of 5Tw or more, the recording pulse is made up of the head,comb-shaped and tail pulses. When it is desired to form a second statearea for the NRZI signal having a length of 4Tw, the recording pulse ismade up of the head and tail pulses. When it is desired to form a secondstate area for the NRZI signal having a length of 3Tw, the recordingpulse is made up of a single pulse.

[0028] A power level equal to or lower than the bias level 1 and equalto or higher than the bias level 3 is set and is referred to as the biaslevel 2. Following the tail pulse for 4Tw or more and following thewrite light pulse for 3Tw, the power level of the energy beam is held atthe bias level 2 for a predetermined time.

[0029] There is possibility that the bias level 2 is equal to either oneof the bias levels 1 and 3. Or there is possibility that the write leveland bias levels 2 and 3 are all exactly at the same power level. Thereis a case where reference values of the write level and bias levels 1, 2and 3 are previously recorded at suitable locations on the recordingmedium as medium information. In this case the locations of therecording medium where the medium information relating to the recordingstrategy is recorded are referred to as information tracks for a controldata zone. The reference values of the power levels are read out fromthe information tracks of the control data zone on the recording mediumto determine each power level in a write mode.

[0030] Consider in FIG. 1 a case where it is desired to form a secondstate area on the recording medium for the NRZI signal having a lengthof 4Tw or more and to define a recording waveform. A time elapsed byT_(EFP) from a rising edge of the NRZI signal defines a falling edge ofthe head pulse in a write pulse train. Further, a rising edge of thehead pulse is present at a time earlier by a time T_(FP) from filefalling edge of the head pulse. This naturally means that, if theelapsed time from the rising edge of the NRZI signal to the rising edgeof the head pulse is defined as T_(SFP), the relationship betweenT_(EFP), T_(SFP) and T_(FP) becomes T_(EFP)=T_(SFP) +T_(FP).

[0031] A rising edge of the tail pulse in the write pulse train ispresent at a time elapsed by a time T_(SLP) from a reference timeearlier by a time 2Tw than a falling edge time of the NRZI signal. At atime elapsed by a time T_(ELP) from the rising edge time of the tailpulse, there is present a falling edge of the tail pulse. This naturallymeans that, if the elapsed time from the reference time earlier by atime 2Tw than a falling edge of NRZI signal to the falling edge of thetail pulse is defined as T_(ELP), the relationship between T_(SLP),T_(ELP) and T_(LP) becomes T_(ELP)=T_(SLP)+T_(LP).

[0032] There may sometimes be present a comb-shaped pulse train betweenthe head and tail pulses. Rising edges of pulses in the comb-shapedpulse train coincide with the position of the reference clock. At a timeelapsed by the time T_(MP) from the rising edge time of each pulse, thepulse falls.

[0033] Consider a case where it is desired to form on the recordingmedium a second state area corresponding to the NRZI signal of 3Tw.Assuming that a time elapsed by a time T_(EFP) from a rising edge of theNRZI signal is set as a reference time, then there exists a rising edgein a light pulse at a time earlier by the time T_(FP) from the referencetime. This naturally means that, if the elapsed time from the risingedge of the NRZI signal to the rising edge of the light pulse is definedas T_(SFP), the relationship between T_(EFP), T_(SFP) and T_(FP) becomesT_(EFP)=T_(SFP)+T_(FP).

[0034] Further, when a time earlier by a time 2Tw from the falling edgetime of the NRZI signal is set as a reference time and a time elapsed bythe time T_(SLP) from the reference time is set as a second referencetime, the light pulse falls at a time elapsed by a time T_(LP) from thesecond reference time. This naturally means that, if the elapsed timefrom the reference time earlier by a time 2Tw from a falling edge ofNRZI signal to a falling edge of the light pulse is defined as T_(ELP),the relationship between T_(SLP), T_(ELP) and T_(LP) becomes T_(ELP),T_(SLP)+T_(LP).

[0035] The last pulse of the NRZI signal of 4Tw or more or the writepulse of the NRZI signal of 3Tw is followed by a duration having a powerlevel of the bias level 2 and having a time length of T_(LC).

[0036] The reference values of the times T_(EFP), T_(SFP), T_(FP)T_(ELP), T_(SLP), T_(LP), T_(LC) and T_(MP) defining the write pulse areread out from the information track of the control data zone, and thesetimes are determined based on the read-out reference values.

[0037] The times T_(EFP), T_(SFP), T_(FP), T_(ELP), T_(SLP), T_(LP),T_(LC) and T_(MP) defining the write pulse are not always limited tohaving their constant values and sometimes may be required to be changeddepending on combinations of the NRZI signals. In particular, in thecase of DVD-RAM having a memory capacity of 4.7 GB per one side as anexample, the NRZI signal of 3Tw as the shortest mark has a length ofabout 0.42 microns that is shorter than a write spot diameter of 0.45microns. When such high density recording is carried out, thermalinterference between adjacent marks becomes great, which, in some cases,makes it difficult to realize the recording always stably. To avoidthis, it is considered to change the write waveform to a suitable formaccording to the combinations of the NRZI signals. In order to correct ashift in the leading edge, any of the times T_(EFP) and T_(FP) ischanged. Changes in these times from the reference values thereof arereferred to as ΔT_(EFP) and T_(TFP) respectively.

[0038] If T_(EFP) is changed by ΔT_(EFP) and T_(FP) is not changed,T_(SFP) changes by ΔT_(EFP). If T_(FP) is changed by ΔT_(FP) and T_(EFP)is not changed, T_(SFP) changes by ΔT_(FP). These changes naturally comefrom the relationship of T_(EFP)=T_(SFP)+T_(FP).

[0039] The changes can be described by the followings with completelythe same meaning. In case T_(EFP) is changed without changing T_(FP),T_(SFP) is changed by ΔT_(SFP) without changing T_(FP). Then T_(EFP) isautomatically changed by ΔT_(SFP). In case T_(FP) is changed withoutchanging T_(EFP), T_(SFP) is changed by ΔT_(SFP) without changingT_(EFP). Then T_(FP) is automatically changed by −ΔT_(SFP).

[0040] The meaning of the two descriptions to correct a shift in theleading edge is completely equivalent. To avoid redundancy, only thefirst description is used in this embodiment. The second description isalways applicable to the part in this embodiment where the firstdescription is employed.

[0041] In order to correct a shift in the trailing edge, any of thetimes T_(SLP) and T_(LP) is changed. Changes in these times from thereference values thereof are referred to as ΔT_(SLP) and ΔT_(LP)respectively.

[0042] If T_(SLP) is changed by ΔT_(SLP) and T_(LP) is not changed,T_(ELP) changes by ΔT_(SLP). If T_(LP) is changed by ΔT_(LP) and T_(SLP)is not changed, T_(ELP) changes by ΔT_(LP). These changes naturally comefrom the relationship of T_(ELP)=T_(SLP)+T_(LP).

[0043] The changes can be described by the followings with completelythe same meaning. In case T_(SLP) is changed without changing T_(LP),T_(ELP) is changed by ΔT_(ELP) without changing T_(LP). Then T_(SLP) isautomatically changed by ΔT_(ELP). In case T_(LP) is changed withoutchanging T_(SLP), T_(ELP) is changed by ΔT_(ELP) without changingT_(SLP). Then T_(LP) is automatically changed by ΔT_(ELP).

[0044] The meaning of the two descriptions to correct a shift in thetrailing edge is completely equivalent. To avoid redundancy, only thefirst description is used in this embodiment. The second description isalways applicable to the part in this embodiment where the firstdescription is employed.

[0045] A first lookup table of T_(MF) for the leading edge will bedefined. The table is a list of values which are determined bycombinations of a length M(n) of a mark being currently written and alength S(n−1) of a space precedent to the mark and which can be positiveor negative. Next a second lookup table of T_(ML) for the trailing edgewill be defined. This table is a list of values which are determined bycombinations of the length M(n) of a mark being currently written and alength S(n+1) of a space subsequent to the mark and which can bepositive or negative.

[0046] In a case 1, the value of T_(MF) is made equal to the value ofΔT_(FP) and the value of T_(ML) is also made equal to the value ofΔT_(LP). In this case, the values of T_(FP) and T_(LP) vary depending oncombinations of the NRZI signals. That is, in the head pulse, its risingedge position varies while its falling edge position is stationary. Inthe tail pulse, on the other hand, its rising edge position isstationary while its falling edge position varies.

[0047] If the second description to correct a shift in the leading andthe trailing edge is used, the description for case 1 is as follows. Thevalue of T_(MF) is made equal to the value of T_(SFP) without changingthe value of T_(EFP). The value of T_(ML) is made equal to the value ofT_(ELP) without changing the value of T_(SLP). The meaning of thisdescription is perfectly the same as the first one.

[0048] In a case 2, the value of T_(MF) is made equal to the value ofΔT_(EFP) and the value of T_(ML) is made equal to the value of ΔT_(LP).In this case, the values of T_(EFP) and T_(LP) vary depending oncombinations of the NRZI signals. That is, in the head pulse, its risingand falling edge positions vary at the same time. In the tail pulse, onthe other hand, its rising edge position is stationary while its fallingedge position varies.

[0049] In a case 3, the value of T_(MF) is made equal to the value ofΔT_(FP) and also the value of T_(ML) is made equal to the value ofΔT_(SLP). In this case, the values of T_(FP) and T_(SLP) vary dependingon combinations of the NRZI signals. That is, in the head pulse, itsrising edge position varies while its falling edge position isstationary. In the tail pulse, on the other hand, its rising and fallingedge positions vary at the same time.

[0050] In a case 4, the value of T_(MF) is made equal to the value ofΔT_(EFP) and also the value of T_(ML) is made equal to the value ofΔT_(SLP). In this case, the values of T_(EFP) and T_(SLP) vary dependingon combinations of the NRZI signals. That is, in the head pulse, itsrising and falling edge positions vary at the same time in the tailpulse, on the other hand, its rising and falling edge positions vary atthe same time.

[0051] If the second description to correct a shift in the leading andtrailing edges is used, the description for case 2 is as follows. Thevalue of T_(MF) is made equal to the value of T_(SFP) without changingthe value of T_(FP). The value of T_(ML) is made equal to the value ofT_(ELP) without changing T_(LP). The meaning of this description isperfectly the same as the first one.

[0052] In a case 5, the value of T_(MF) is made equal to the value ofΔT_(FP). In this case, the value of T_(FP) varies depending oncombinations of the NRZI signals. That is, in the head pulse, its risingedge position varies while its falling edge position is stationary.

[0053] In a case 6, the value of T_(MF) is made equal to the value ofΔT_(EFP). In this case, the value of T_(EFP) varies depending oncombinations of the NRZI signals. That is, in the head pulse, its risingand falling edge positions vary at the same time.

[0054] In a case 7, the value of T_(ML) is made equal to the value ofΔT_(LP). In this case the value of T_(LP) varies depending oncombinations of the NRZI signals. That is, in the tail pulse, its risingedge position is stationary while its falling edge position varies.

[0055] In a case 8, the value of T is made equal to the ML value ofΔT_(SLP). In this case, the value of T_(SLP) varies depending oncombinations of the NRZI signals. That is, in the tail pulse, its risingand falling edge positions vary at the same time.

[0056] The values included in the first and second lookup tables andinformation on selection of any of the cases 1 to 8 are determined byreading information written in the information track of the control datazone on the recording medium.

[0057] As has been explained above, since adaptive waveform changesbased on the lookup tables are divided into the cases 1 to 8 and any ofthe cases is selected, the method of the present invention canadvantageously cope with recording media having various characteristicsand can record information always stably with good compatibility.

[0058] In the present embodiment, the first lookup table was defined tohave 4×4 cases of 4 sorts of M(n)×4 sorts of S(n−1). The second lookuptable was defined to have 4×4 cases of 4 sorts of M(n)×4 sorts ofS(n+1). However, the size of the lookup table is not limited to the 4×4cases but may be set at any cases other than 1×1 to realize the effectsof the present invention. Further, although each of the first and secondlookup tables forms a two-dimensional table in the present embodiment,it may advantageously be a three-dimensional table based on acombination of three parameters of S(n−1), M(n) and S(n+1) or may bemulti-dimensional table. The simplicity and/or complexity of the tablemay be suitably determined by various factors including characteristicsof a recording medium and a demanded recording accuracy. When a DVD-RAMhaving a memory capacity of 4.7 GB for one side is used as an example,its lookup table is desirably a two dimensional table having a size ofabout 3×3, 4×3, 3×4 or 4×4.

[0059] Now explanation will be made as to mark edge controllability inconnection with the cases 1 and 4 as an example. Several experimentalresults are shown herein. In this connection, their experimentalconditions are set so that a linear speed is about 8 m/sec., T is about17 nsec., a 3T mark as the shortest mark has a physical length of about0.4 μm or slightly more, a track pitch is about 0.6 μm, a peak power is11 mW, the bias power 1 is 4.5 mW, the bias power 2 is 3.5 mW and thebias power 3 is 1 mw.

[0060] A single mark having a specific length is recorded always underthe same conditions, which is referred to as the anchor mark. Followinga space (corresponding to an area having no recorded mark betweenadjacent recording marks) subsequent to the anchor mark, a mark to bemeasured (which will be sometimes referred to as the measurement mark)is recorded. A recording pulse for the measurement mark is controlledaccording to the above case 1 or 4. A reproduction signal obtained byreproducing the anchor mark and measurement mark is digitized intopredetermined slice levels to obtain a binary data signal. The binarydata signal is used to measure a time interval (leading edge interval)from the leading edge of the anchor mark to the leading edge of themeasurement mark. Further, the binary data signal is used to measure atime interval (trailing edge interval) from the trailing edge of theanchor mark to the trailing edge of the measurement mark.

[0061] Shown in FIG. 2A are variations in the leading edge interval andshown in FIG. 2B are variation in the trailing edge interval when thetail pulse position is stationary while the head pulse position variesin the case 4. In the drawings, their plus directions of axes are timeadvancing directions. In the drawings, the lengths of the measurementmark are used as parameters. In FIG. 2A, the head pulse position andmark leading edge position are in a nearly linearly proportionalrelationship. In FIG. 2B, on the other hand, as the head pulse positionmoves, the trailing edge correspondingly moves. A movement of thetrailing edge amounts even to about 50% of a movement of the head pulseposition.

[0062] Shown in FIG. 3A are variations in the trailing edge interval andshown in FIG. 3A are variation in the leading edge interval when thehead pulse position is stationary while the tail pulse position variesin the case 4.

[0063] In the drawings, their plus directions of axes are time advancingdirections. In the drawings, the lengths of the measurement mark areused as parameters. In FIG. 3A, the tail pulse position and marktrailing edge position are in a nearly linearly proportionalrelationship. In FIG. 3B, on the other hand, as the tail pulse positionmoves, the leading edge correspondingly moves. A movement of the leadingedge amounts even to about 50% of a movement of the tail pulse position.

[0064] Shown in FIG. 4A are variations in the leading edge interval andshown in FIG. 4B are variations in the trailing edge interval when thetail pulse rising and falling positions are stationary while the headpulse rising position varies in the case 1. In the drawings, their plusdirections of axes are time advancing directions. In the drawings, thelengths of the measurement mark are used as parameters. In FIG. 4A, thehead pulse rising edge position and mark leading edge position are in anearly linearly proportional relationship. In FIG. 4B, on the otherhand, even when the leading edge position of the head pulse moves, thiscauses substantially no remarkable movement of the mark trailing edgeposition at least in a range where the leading edge position of the headpulse less varies.

[0065] Shown in FIG. 5A are variations in the trailing edge interval andshown in FIG. 5B are variations in the leading edge interval when therising and falling edge positions of the head pulse are stationary whilethe falling edge position of the tail pulse varies in the case 1.

[0066] In the drawings, their plus directions of axes are time advancingdirections. In the drawings, the lengths of the measurement mark areused as parameters. In FIG. 5A, the tail pulse falling edge position andmark trailing edge position are in a nearly linearly proportionalrelationship. In FIG. 5B, on the other hand, even when the trailing edgeposition of the tail pulse moves, this causes substantially noremarkable movement of the mark leading edge position at least in arange where the trailing edge position of the tail pulse less varies.

[0067] When comparison is carried out between the case 4 of FIGS. 2A, 2Band 3A, 3B and the case 1 of FIGS. 4A, 4B and 5A, 5B, it will be notedfrom the experimental results shown herein that the case 1 is morepreferable with respect to the recording medium and recording strategyused in the experiments. This is because, in the case 1, the leadingedge position of the record mark can be controlled independently only bythe rising edge position of the head pulse in the recording pulse, andthe trailing edge position of the recording medium can be controlledindependently only by the falling edge position of the tail pulse in therecording pulse. The case 4 is more deteriorated in the controlindependency and more difficult in the control than the case 1.

[0068] Although the case 1 is more preferable than the case 4 withrespect to the recording medium and recording strategy used in theexperiments, there is a case where the case 4 is more preferable thanthe case 1 depending on the design of the recording medium. Morespecifically, in the case 1, the energy per se possessed by the head ortail pulse is increased or decreased, so that, when the energy of thehead or tail pulse is excessively increased, this results indeterioration of overwrite or cross-erase characteristics. In the case4, on the other hand, since the energy possessed by the entire recordingpulse train varies only slightly, there is no likelihood ofdeterioration of such overwrite or cross-erase characteristics, it goeswithout saying that, when sufficient margins are given to overwrite orcross-erase characteristics in the design of the recording medium, therecan be designed a recording medium without any possibility ofdeterioration of the overwrite or cross-erase characteristics even inthe case.

[0069] Explanation will then be made as to another embodiment of thepresent invention with reference to FIG. 6 showing an informationstorage apparatus in the form of a block diagram. For the convenience ofexplanation, a recording medium 100 is illustrated as mounted in theinformation storage apparatus. For the purpose of storing information,the recording medium 100 is indispensable, but it may be dismounted fromthe information storage apparatus or be mounted thereinto as necessary.

[0070] In FIG. 6, a chucking mechanism 112 is mounted to a rotary shaft111 of a motor 110 attached to a casing 108 so that the chuckingmechanism 112 holds a recording medium 100.

[0071] The chucking mechanism 112 acts to hold the recording medium 100.The motor 110, rotary shaft 111 and chucking mechanism 112 form amechanism for relatively moving the recording medium 100 and an energybeam.

[0072] Mounted to the casing 108 is a rail 115. A rail guide 116 guidedby the rail 115 is mounted to a case 117. Also mounted to the case 117is a linear gear 119, to which a rotary gear 120 is mounted.Transmission of rotation of the rotating motor 118 mounted on the casing108 to the rotary gear 120 causes linear movement of the case 117 alongthe rail 115. The linear movement is directed toward nearly the radialdirection of the recording medium 100.

[0073] Mounted to the case 117 is a magnet 121. Also mounted to the case117 is an objective lens 130 through a suspension 123 which can be movedonly in two directions, that is, in a direction of nearly a normal ofthe recording surface of the recording medium 100 and in a nearly radialdirection of the recording medium 100. Mounted onto the objective lens130 is a coil 122 as nearly opposed to a magnet 121. When a currentflows through the coil 122, its magnetic effect causes the objectivelens 130 to be able to move in two directions of the direction of nearlya normal of the recording surface of the recording medium 100 and thenearly radial direction of the recording medium 100. The rail 115, railguide 116, case 117, magnet 121, suspension 123, coil 122 and objectivelens 130 form a mechanism which positions the energy beam at apredetermined position on the recording medium 100.

[0074] Mounted to the case 117 is a semiconductor laser 131 as an energybeam generator. The energy beam emitted from the semiconductor laser 131passes through a collimating lens 132 and a beam splitter 133 and thenthrough the objective lens 130. Part of the light emitted from theobjective lens 130 is reflected by the recording medium 100, passedthrough the objective lens 130, reflected by the beam splitter 133,condensed by a detection lens 134, and then an intensity of thereflected light is then detected by a photodetector 135. More in detail,the photodetector 135 has a plurality of divided light receiving areas.Intensities of light detected on the respective areas are amplified andcalculated by an amplifier 152 to detect information (servo signal)indicative of a relative positional relationship between a light spotfocused by the objective lens 130 and the recording medium 100 as wellas an information read signal. The servo signal is sent from theamplifier to a servo controller 151, whereas the read signal is sentfrom the amplifier to a decoder 153.

[0075] When the recording medium 100 is loaded into the informationstorage apparatus and the chucking mechanism 112 fixedly holds therecording medium 100, a detector 140 detects the presence of the mediumand sends a signal indicative of the medium presence to a systemcontroller 150. The system controller 150, when receiving the signal,controls the motor 110 in such a manner that the recording medium 100 isrotated at a suitable rotational speed. The system controller 150 alsocontrols a rotating motor 118 in 3uch a manner that the case 117 islocated at a suitable position. The system controller 150 also causesthe semiconductor laser 131 to controllably emit light, an also causes aservo controller 151 to be operated so that the rotating motor 118 isdriven or a current flows through the coil 123 to position the lightspot focused by the objective lens 130 at a predetermined position onthe recording medium 100. The servo controller 151 then sends a signalindicative of the focused spot formed on the recording medium 100 to thesystem controller 150. The system controller 150, when receiving thesignal, sends an instruction to a decoder 153 to decode the read signaltherein. When a read track is not an information track in the controldata zone, the system controller 150 sends an instruction to the servocontroller 151 such that the focused spot is positioned at aninformation track in the control data zone. As a result of the aboveoperation, the system controller 150 reads the information track of thecontrol data zone and reads out medium information recorded therein.

[0076] Written in the information track of the control data zone aresuch recording strategy parameters as already explained in connectionwith FIG. 1. That is, the system controller 150 reads out from therecording medium 100 information on the recording power level, timerelations between recording pulses, lookup table, and the adaptivecontrol set to any of the cases 1 to 8. The system controller 150 writesthese recording strategy parameters in a parameter table of a signalprocessing circuit 154, a parameter table of a timing controller ordelay circuit 155, and a current sink parameter of current sinks 156.The operations of the cases 1 to 8 explained in FIG. 1 can be realizedby changing the writing method into the table of the delay circuit 155depending on the selection of the cases 1 to 8 or by switching switchesof a delay circuit 155. Incorporated in the delay circuit 155 are firstto fourth timing adjusting means. Also incorporated in the delay circuit155 is a first change-over mechanism for switching between the first andsecond timing adjusting means. Further incorporated in the delay circuit155 is a second change-over mechanism for switching between the thirdand fourth timing adjusting means.

[0077] The timing of the system controller 150 of reading the recordingstrategy parameters from the recording medium 100 and writing theseparameters in the parameter table of the signal processing circuit 154,the parameter table of the delay circuit 155 and the current sinkparameter of the current sinks 156 may be set only when the recordingmedium 100 is put in its writable state. For example, when the recordingmedium 100 is placed in its write protect state, as when a write protectswitch provided on a case of the recording medium 100 is set at itswrite protect position or as when an upper-level controller of theinformation storage apparatus issues a write protect command; a seriesof operations such as the reading of the recording strategy parameterscan be omitted. For the purpose of detecting a write protect switch, thedetection switch 141 is mounted to the casing 108 and sends its detectedsignal to the system controller. In the recording protection mode, apreparation time taken after the loading of the recording medium 100 inthe chucking mechanism 112 until the medium reaches its reproduciblestate can be shortened by stopping the reading of the recording strategyparameters.

[0078] When receiving an information reproduction command from theupper-level controller through the input connector 159, the systemcontroller 150 issues a command to the servo controller 151 to positionthe focused spot at a suitable position on the recording medium 100, asignal obtained from the photodetector 135 is decoded by the decoder 153to obtain read information, and then the read information is sent fromthe decoder 153 through an output connector 158 to the upper-levelcontroller.

[0079] When receiving an information write command and write information(to be written) from the upper-level controller via an input connector159, the system controller 150 issues a command to the servo controller151 to position the focused spot at a suitable position on the recordingmedium 100. Further, the write information is converted by the signalprocessing circuit 161 to an NRZI signal. The converted NRZI signal isconverted by the signal processing circuit 154 to a suitable train of aplurality of pulses. The pulse train is passed through the delay circuit155 and transmitted to the current sinks 156. In the illustratedexample, the signal processing circuit 154 and signal processing circuit161 form a signal processing circuit which converts the write signal tothe recording pulse trains.

[0080] A fixed current controller 157 is connected to the semiconductorlaser 131 so that a total of currents consumed by the semiconductorlaser 131 and current sinks 156 has always a constant value. Theplurality of current sinks 156 are connected to the fixed currentcontroller 157. Whether or not the current sinks 156 are operated toabsorb the current depends on the signal generated by the signalprocessing circuit 154 and passed through the delay circuit 155. Whenthe current sinks 156 are operated, a part of the current issued fromthe fixed current controller 157 is absorbed by the current sinks 156,resulting in reduction of a current flowing into the semiconductor laser131. This causes the energy level of the energy beam emitted from thesemiconductor laser 131 to be varied. The signal processing circuit 154and delay circuit 155 realize such a recording strategy as shown in FIG.1 when the plurality of current sinks 156 are operated with suitabletiming.

[0081] For the above operation, power is externally supplied to theinformation storage apparatus via a terminal 160.

[0082] As has been explained in the foregoing, recording is carried outas modified according to the cases 1 to 8, so that, even when suchhigh-density recording is carried out as the shortest mark length is therecording spot radius or less, the information recording canadvantageously be carried out independently of the characteristics ofthe recording medium and with good compatibility and good stability.Further, since the present invention uses such a recording medium as tobe able to record information about selection of any of the cases 1 to 8in the information track of the control data zone on the recordingmedium, there is provided a recording medium which can recordinformation with a high density independently of fluctuations inrecording characteristics of the information storage apparatus alwayswith good stability and compatibility.

[0083] Further, since the information about selection of any of thecases 1 to 8 is read out from the recording medium 100 and is used toreflect it on the state of the information storage apparatus, there areprovided a recording method and an information storage apparatus whichcan record information always with good stability, and compatibility andwith a high density.

[0084] In accordance with the foregoing embodiments, even when suchhigh-density recording is carried out as the shortest recording marklength is the recording spot radium or less, information can be recordedon a recording medium independently of characteristics of the recordingmedium or on characteristics of the information storage apparatus,always with good compatibility and stability.

What is claimed is:
 1. A recording medium for use with an informationrecording apparatus which has a timing adjusting controller to adjust atiming of a recording pulse comprising: a disk-like substrate; at leastone track being provided on the disk-like substrate; and a zoneincluding said at least one track; wherein said zone stores informationrelating to a predetermined timing of a pulse for said recording mediumwhich is detected by said apparatus.
 2. A recording apparatus forrecording information on a recording medium comprising: a detector whichdetects information stored on the recording medium relating to apredetermined timing of a recording pulse for said recording medium; anda controller which adjusts a timing of a recording pulse which isrecorded on the medium based on the information detected by saiddetector.